Strategies for understanding and preventing adolescent substance use and other health risk behaviors have in recent years become increasingly couched in a risk and protective factor framework. Epidemiologically- based prevention approaches rooted in this framework seel to assess the levels of risk and protective factors in individuals or groups and then select and implement specific strategies that will effectively reduce elevated risk factors and/or enhance protective factors. Although research has identified numerous and interrelated risk factors for substance use among youth over the past two decades, very few studies have simultaneously examined comprehensive sets of putative risk and factors with large and nationally representative samples. The integration of findings from prior studies has been hampered by differences across these studies with respect to their target populations and sample sizes, measures, and other methodological features. The proposed study seeks to advance our understanding of risk factors for adolescent substance use by utilizing a single, nationally representative cross-sectional survey of the adolescent household population and their parents and examining a comprehensive set of hypothesized risk factors across multiple domains. We will utilize the 1999 National Household Survey on Drug Abuse (NHSDA) for this purpose. The large NHSDA sample will enable the investigators to assess the relationship between risk/protective factors and substance use for a broad range of substances and stages of substance use, and to examine how these relationships vary by age, gender, racial/ethnic group, and other demographic variables. Multivariate logistic modeling procedures will be applied for these purposes. Although the cross-sectional nature of the 1999 NHSDA precludes definitive assessment of temporal ordering of the variables within the relationships to be investigated, the proposed study will provide a strong empirical basis on which to establish the existence, strength, and robustness of the associations between an expansive set of risk and protective factors and adolescent substance use behaviors.